The present invention relates to releasable electrical connecting means for the connection of an electrode to an implantable artificial cardiac pacemaker.
In an artificial cardiac pacemaker it is necessary to electrically conductively connect the electrode which serves to transmit pulses from or to the heart to an input or output of the pacemaker circuit, and the connection itself must be electrically insulated with respect to the conductive material of the cardiac pacemaker housing. Moreover, the connection must not impair the fluid-tightness of the housing against attack by body fluids.
There already exist various screw-in or plug-in connections for connecting an electrode to a pacemaker but many of them have the drawback of not being sufficiently fluid-tight to protect the interior of the pacemaker against the penetration of body fluids over a period of many years. Other known connection devices do not have a sufficiently high resistance to corrosion.
In the case of pacemakers using batteries that permit continuous operation for periods of the order of 10 years or more, the connection device must satisfy even more stringent requirements relative to durability and ability to withstand the influences to which they will be subjected in the implanted state. These requirements in particular are not met by the presently known plug-in and screw-in connections.
In addition, in order to reduce the costs involved in the use of artificial cardiac pacemakers, it has been found desirable to make them reusable. It is possible, in principle, to reuse a pacemaker after it has been sterilized, i.e., to implant it in another patient. The prerequisite is, however, that the pacemaker housing be capable of being sterilized in such a manner as to remove all contaminants which may be damaging to the new user. It seems that this requirement can be met only if the pacemaker does not contain any parts made of an epoxide material which may come into contact with the body of the patient, or at least if the surface of the epoxide material exposed to body fluids is minimal. However, most of the known electrode connecting means include components which have large exposed surfaces of epoxide material and this limits reuse of the pacemaker.
In other types of implantable artificial cardiac pacemakers, the contact element which is attached to the pacemaker housing in order to connect an external electrode is rigidly connected with a sealing and insulating passage through the housing. If this contact element is subjected to mechanical stresses, or if the plug for the electrode is removed, there then exists the danger of tearing of the sealing element and the hermetic seal of the pacemaker is no longer assured.